High-resistivity particle-matrix composite materials, downhole tools including such composite materials, and related methods

ABSTRACT

A particle-matrix composite material comprises a metal alloy phase, the metal alloy having a resistivity of at least about seven hundred and fifty (750) nano-ohms per meter, and a composite phase comprising ceramic particles dispersed throughout portions of the metal alloy phase. The composite phase extends throughout the particle-matrix composite material in a substantially three-dimensional network, and regions of the composite phase at least partially surround regions of the metal alloy phase that are free of the ceramic particles. Methods of forming a particle-matrix composite body include coating particles of metal alloy with relatively finer particles of ceramic, partially compacting the coated particles of metal alloy, and heating the partially compacted particles of metal alloy to form a substantially continuous metal alloy matrix with ceramic particles dispersed therein. Downhole tools including components comprising particle-matrix composite materials are also disclosed.

TECHNICAL FIELD

Embodiments of the present disclosure relate to particle-matrix composite materials, downhole tools including such materials, and related methods.

BACKGROUND

Data acquisition in downhole environments is an important consideration in oil, gas, geothermal, and other drilling operations. For example, automated drilling processes require a reliable and accurate data stream providing information regarding downhole conditions and formation characteristics. Detailed formation data can also be used to enhance production from that formation through directional drilling and other methods. Such data collection may be generally referred to as logging while drilling (LWD) and measurement while drilling (MWD).

One formation characteristic susceptible to measurement is resistivity. The measured resistivity of the formation can provide information about formation composition, moisture content, petroleum content, etc. Tool bodies of LWD/MWD tools may be formed from metal alloys such as steel, or may be formed from conventional particle-matrix composite materials including metal alloy matrix materials, such as bronze or steel. Such metal alloys may have relatively high electrical conductivity and may interfere with the operation of the resistivity tool through, e.g., formation of eddy currents in the tool body and/or other undesirable electromagnetic phenomena. Consequently, a conductive tool body may limit the range of a resistivity tool (i.e., the maximum distance from the tool laterally into the formation intersected by a wellbore in which the resistivity tool is disposed at which accurate data can be obtained). However, conventional materials having higher resistivity than conventional tool body materials may lack the high tensile strength and toughness required for such tool bodies to withstand the harsh high-temperature, high-pressure wellbore environment.

BRIEF SUMMARY

In one aspect of the disclosure, a downhole tool includes a tool body including at least one component comprising a particle-matrix composite material. The particle-matrix composite material comprises a metal alloy phase, the metal alloy of the metal alloy phase having a resistivity of at least about seven hundred and fifty (750) nano-ohms per meter, and a composite phase comprising ceramic particles dispersed throughout portions of the metal alloy phase. The composite phase extends throughout the particle-matrix composite material in a substantially three-dimensional network, and regions of the composite phase at least partially surround regions of the metal alloy phase that are free of the ceramic particles.

In another aspect of the disclosure, a method of forming a particle-matrix composite body includes coating particles of metal alloy with relatively finer particles of ceramic, partially compacting the coated particles of metal alloy, and heating the partially compacted coated particles of metal alloy to form a substantially continuous metal alloy matrix with ceramic particles dispersed therein.

In yet another aspect of the disclosure, a particle-matrix composite material includes a metal alloy phase, the metal alloy having a resistivity of at least about seven hundred and fifty (750) nano-ohms per meter, and a composite phase comprising ceramic particles dispersed throughout portions of the metal alloy phase. The composite phase extends throughout the particle-matrix composite material in a substantially three-dimensional network, and regions of the composite phase at least partially surround regions of the metal alloy phase that are free of the ceramic particles.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present invention, various features and advantages of disclosed embodiments may be more readily ascertained from the following description when read with reference to the accompanying drawings, in which:

FIG. 1A is an optical photomicrograph at 200× magnification of a particle-matrix composite material according to one embodiment of the disclosure;

FIG. 1B is a simplified schematic diagram of a composite region of the particle-matrix composite material at a higher magnification than the magnification of the photomicrograph of FIG. 1A;

FIG. 2 is a simplified, cross-sectional schematic diagram of unconsolidated particles of a particle-matrix composite material of the disclosure;

FIG. 3 is a perspective view of a downhole tool having a tool body that may comprise a particle-matrix composite material as described herein;

FIG. 4 is a graph showing resistivity as a function of alumina content for embodiments of particle-matrix composite material as described herein; and

FIG. 5 is a graph showing Young's modulus as a function of alumina content for embodiments of particle-matrix composite material as described herein.

DETAILED DESCRIPTION

The illustrations presented herein may not be actual views of any particular material or downhole tool, but are merely idealized representations employed to describe embodiments of the present disclosure. Additionally, elements common between figures may retain the same numerical designation.

FIG. 1A shows an optical photomicrograph of an embodiment of a high-resistivity particle-matrix composite material 100 at a magnification of about 200×. In the embodiment of FIGS. 1A and 1B, the particle-matrix composite material 100 may comprise a substantially continuous metallic phase 102 and a composite phase 104 including hard material (e.g., ceramic) particles 105 (FIG. 1B) finely dispersed throughout the metallic phase 102. FIG. 1B is a simplified, schematic view of the composite phase 104, as it may appear under magnification of at least about an order of magnitude greater than the magnification of the photomicrograph of FIG. 1A (e.g., a magnification of at least about 2000×). The ceramic particles 105 may comprise a ceramic material that exhibits a high electrical resistivity relative to the material of the continuous metallic phase 102. The ceramic particles 105 may comprise, as non-limiting examples, materials such as cubic boron nitride (c-BN), silicon nitride (Si₃N₄), or aluminum oxide (Al₂O₃).

The metallic phase 102 may comprise a metal alloy. In some embodiments, the metallic phase may be an alloy of at least iron and carbon, i.e., steel. The metal alloy of the metallic phase 102 may include alloying elements that contribute to formation of gamma-phase iron (γ-Fe) (i.e., austenite). The metallic phase 102 may also comprise other phases of iron alloy, e.g., martinsite, in addition to or in place of γ-Fe. In some embodiments, the metallic phase 102 may comprise stainless steel (e.g., an alloy of at least iron, carbon, and chromium), or high-manganese steel (e.g., an alloy of at least iron, carbon, and manganese), as discussed in further detail below. In particular, the metallic phase 102 may comprise a metal or metal alloy (such as steel, Ti, Ni alloys, etc.) that exhibits a relatively high electrical resistivity (or relatively low electrical conductivity) relative to conventional metals and metal alloys typically used in downhole tool bodies.

Due to the manner of fabrication of the particle-matrix composite material 100, which is described in further detail below, the ceramic particles 105 may be characterized as being dispersed throughout the metallic phase 102. For example, the ceramic particles 105 may be dispersed discontinuously in a three-dimensional network extending around relatively larger regions that consist essentially of the metallic phase 102 and that are at least substantially free of the ceramic particles 105. For example, as shown in FIG. 1A, the metallic phase 102 may include regions having an average grain size of between about 10 micrometers and about 100 micrometers that are substantially free of the ceramic particles 105. Average grain size may be determined using standardized test methods, e.g., ASTM E112-13 (Standard Test Methods for Determining Average Grain Size). Regions of the composite phase 104 may at least partially surround the regions of the metallic phase 102 that are substantially free of the ceramic particles 105. As a non-limiting example, the ceramic particles 105 may comprise between about 5 weight percent and about 30 weight percent of the particle-matrix composite material 100.

The particle-matrix composite material 100 may have a bulk electrical resistivity ρ greater than about 1000×10⁻⁹ ohms per meter (1000 nano-ohms per meter). For example, in some embodiments, the particle-matrix composite material may have a bulk resistivity greater than about 1500 nano-ohms per meter, or greater than about 2000 nano-ohms per meter. The composition of the metallic phase 102 may contribute to the increased resistivity of the particle-matrix composite material. For example, the metal alloy may include one or more alloying elements that increase the resistivity of the alloy and thus the resistivity of the particle-matrix composite material. In some embodiments, the metal alloy may comprise manganese, which has a resistivity of 1,440 nano-ohms per meter. In comparison, pure iron has a resistivity of about 961 nano-ohms per meter. The addition of manganese as an alloying element may increase the resistivity of the bulk metal alloy by, e.g., partially impeding electron movement through the iron. Presence of the hard material particles of the discontinuous phase 104 may similarly increase the resistivity of the bulk material.

In some embodiments, the metallic phase 102 may include a steel alloy known as Hadfield's Steel (alternatively known as Mangalloy). Such steels may be characterized by a mass ratio of manganese to carbon of about equal to or greater than 10:1. As one specific, non-limiting example of such a steel, the metal alloy may comprise between about 12.1 weight percent and about 14.8 weight percent manganese, between about 16.0 weight percent and about 19.0 weight percent chromium, between about 0.5 weight percent and about 1.8 weight percent nickel, and between about 0.005 weight percent and about 0.08 weight percent carbon, with the balance being iron. Small amounts (<1 weight percent) of one or more of silicon, nitrogen, molybdenum, copper, phosphorus, and sulfur may also be present in the metal alloy.

As an additional specific, non-limiting example of a high-manganese steel, the metal alloy may comprise DATALLOY 2®, available from Allegheny Technologies Incorporated, 1000 Six PPG Place, Pittsburgh, Pa. 15222 USA. A typical DATALLOY 2® composition may include about 15.1 weight percent manganese, about 15.3 weight percent chromium, about 2.3 weight percent nickel, about 2.1 weight percent molybdenum, about 0.40 weight percent nitrogen, and about 0.03 weight percent carbon, with the balance being iron, and impurities may also be present.

As yet another specific, non-limiting example of a high-manganese steel, the metallic phase may comprise about 32.44 weight percent manganese, 6.78 weight percent aluminum, 5.74 weight percent chromium, 0.99 weight percent carbon, balance iron and impurities. Such an alloy is available from North American Höganäs, 111 Hoganas Way, Hollsopple, PA 15935 USA.

In some embodiments, the metallic phase 102 may comprise stainless steel (e.g., a steel alloy including at least about ten weight percent chromium). One non-limiting example of a suitable stainless steel alloy is 17-4 PH available from North American Höganäs. The 17-4PH alloy may include between about 15.50 and about 17.50 weight percent chromium, between about 3.00 and about 5.00 weight percent copper, between about 3.00 and about 5.00 weight percent nickel, up to about 0.03 weight percent carbon, with the balance being iron, and impurities may also be present.

It should be understood that the above alloy compositions are provided merely as examples of suitable alloys, and that other iron-based and non-iron-based metal alloys (Ti, Ni, etc.) with compositions differing from the above are contemplated within the scope of the disclosure. As a non-limiting example, alloy compositions exhibiting a resistivity of above about 750 nano-ohms per meter may be suited for embodiments of the disclosure.

In addition to the chemical composition of the particle-matrix composite material 100 contributing to the electrical resistivity of the particle-matrix composite material 100, the particle-matrix composite material 100 may be formed to have a microstructure that further contributes to the increased electrical resistivity of the particle-matrix composite material 100. Furthermore, the microstructure of the particle-matrix composite material may enable the particle-matrix composite material to exhibit bulk characteristics of strength and toughness similar to the strength and toughness characteristics of the metal alloy of the metal alloy phase 102. The microstructure may be primarily a function of the manner in which the particle-matrix composite material 100 is formed, as described below.

A process of forming a body comprising the particle-matrix composite material 100, as described herein, may include coating relatively larger particles of metal alloy with finer, relatively smaller, particles of ceramic. The coated metal particles may be compacted into a preform and consolidated in a sintering process, which may involve, for example, application of heat and pressure in a hot isostatic pressing operation, a hot press, an extrusion process, or other consolidation methods. The body of particle-matrix composite material may also undergo heat treatment processes such as solution treatment, quenching, aging, etc., as described in greater detail below.

In some embodiments, the metal alloy may be obtained from a supplier or otherwise provided in powdered form. For example, the metal alloy may be available in powdered form in an ASTM mesh size, e.g., −325 mesh, +325 mesh, +200 mesh, +150 mesh, etc. In other embodiments, the metal alloy may be formed by obtaining elemental powders of the various alloying elements, combining the elemental powders in appropriate fractions, and melting the elemental powders to form the desired alloy. The molten metal alloy may be atomized by forcing the melted alloy through an orifice and allowing molten droplets leaving the orifice to cool and solidify into metal alloy powder. In yet other embodiments, the elemental powders may be combined in the desired ratios and mechanically alloyed, e.g., by high-energy milling of the powders in a ball mill.

The metal alloy powder may have an average particle size of, for example, between about 10 micrometers and about 100 micrometers. In one embodiment, the metal alloy powder may have an average particle size of between about 40 micrometers and about 45 micrometers. In embodiments in which the alloy powder is supplied in powder form, the supplied powder may have a larger than desired average particle size. Accordingly, in some embodiments, the metal alloy powder may be processed to reduce the average particle size. For example, the metal alloy powder may be placed in a ball mill with grinding media and ball-milled until the desired average particle size is obtained.

The metal alloy powder may be coated with ceramic particles having a smaller average particle size than the average particle size of the metal alloy powder. In some embodiments, the particles of ceramic may have an average particle size equal to about 50 percent or less of the average particle size of the particles of metal alloy. For example, the particles of ceramic may have an average particle size of about 10 percent or less, about 5 percent or less, about 1 percent or less, or about 0.1 percent or less than the average particle size of the particles of metal alloy. As a non-limiting example, the ceramic particles may have an average particle size of between about 0.01 micrometer and about 1 micrometer. In some embodiments, the ceramic particles may have an average particle size of between about 0.03 micrometer and 0.3 micrometer. The ceramic particles may comprise, as non-limiting examples, particles of cubic boron nitride, silicon nitride, or aluminum oxide.

The ceramic particles may be combined with the metal alloy powder to achieve particular weight percentages of the metal and ceramic. For example, the mixture of metal alloy powder and ceramic particles may comprise between about 5 weight percent and about 30 weight percent ceramic, with the balance comprised by the metal alloy. The particular weight percent of ceramic particles may in part determine the characteristics of the finished material. For example, increasing the weight percent of ceramic may increase the electrical resistivity and/or the modulus of elasticity of the particle-matrix composite material, as discussed in further detail below with reference to FIGS. 4 and 5. Moreover, increased weight percentages of ceramic may potentially increase the wear-resistance while reducing the toughness of the composite material.

The metal alloy powder particles may be at least partially coated with the relatively finer ceramic particles. For example, the metal alloy powder and the ceramic powder may be combined within a ball mill drum. Grinding media such as aluminum oxide or quartz spheres or cylinders may be included with the metal alloy powder and ceramic powder. To effect coating of the metal powder particles with the relatively finer ceramic particles, ball milling may be performed at low speeds for extended times. For example, ball milling may be performed for at least about 50 hours, at least about 100 hours, or more. Ball milling may be performed at a speed of about 100 RPM or less, about 80 RPM or less, or about 50 RPM or less. The fine ceramic particles may coat the larger metal alloy particles and form a layer of particulate ceramic material surrounding each metal particle as the powders are intermixed in the ball mill.

FIG. 2 shows a simplified, schematic, cross-sectional view of unconsolidated composite material 106 after ball milling. Metal alloy particles 108 are coated with a layer 110 of fine ceramic particles 112. The unconsolidated composite material 106 may be partially compacted into a preform (e.g., compact, green body, etc.). The preform may be consolidated in a sintering process by applying heat and/or pressure. Under the applied heat and/or pressure, the coated premix particles of the unconsolidated composite material 106 may form an at least substantially continuous metal alloy matrix 102 (FIG. 1A) and a composite phase 104 (FIG. 1A) within which the ceramic particles 112 are finely dispersed.

As described above, the ceramic particles 112 (FIG. 2) may be characterized as being dispersed throughout the metal alloy matrix 102 (FIG. 1A). In other words, some regions of the consolidated particle-matrix composite material 100 (FIG. 1A) (e.g., portions of the continuous metal alloy phase 102) may be substantially free of the ceramic particles 105 (FIG. 1B), while other regions (i.e., the composite phase 104) of the particle-matrix composite material 100 may include the ceramic particles 105. For example, each region of the metal alloy phase 102 substantially free of ceramic particles 105 may correspond generally to a metal alloy particle 108 of the unconsolidated composite material 106 (FIG. 2). The composite phase 104 comprising ceramic particles 105 dispersed in metal alloy may extend in a three-dimensional network surrounding regions of the metal alloy matrix 102 corresponding generally to the metal alloy particles 108 of the unconsolidated composite material 106.

In some embodiments, the unconsolidated composite material mixture, or a partially compacted composite material preform, may be consolidated by hot isostatic pressing. Hot isostatic pressing involves applying heat to an unconsolidated composite material body (e.g., a preform) in a pressurized gas environment. For example, the unconsolidated composite material may be heated to at least about 1900° F. (1040° C.) in an environment of inert gas (e.g., argon) pressurized to at least about 14.7 kilopounds per square inch (ksi) (100 MPa). More specific example hot isostatic pressing conditions are discussed below in connection with Example 1 and Example 2 below. In other embodiments, a component may be formed by hot pressing loose or partially compacted composite material powder in a hot press. Yet other embodiments may involve compaction and densification by an extrusion process, or any other densification or sintering process.

FIG. 3 shows an embodiment of a downhole tool 114 including a particle-matrix composite material 100 (FIG. 1) of the disclosure. The downhole tool 114 may be configured to be attached to or form a portion of a drill string (not shown) and generate data related to the formation (not shown) intersected by a wellbore in which the drill string is disposed. The downhole tool 114 may include a tool body 116 comprising one or more component parts. The tool body 116 may be formed from a particle-matrix composite material 100 as described herein. In some embodiments, the downhole tool 114 may be configured to measure the electrical resistivity of a formation surrounding a borehole in which the downhole tool 114 is disposed for use. Forming the tool body 116 of a particle-matrix composite material as described may reduce interference from the tool body 116 and enable the downhole tool 114 to return relatively more accurate data for depths further into the formation from the downhole tool 116 as compared to downhole tools constructed of conventional materials.

The following examples, Example 1 and Example 2, illustrate possible compositions and processing conditions of two non-limiting example embodiments of the disclosure.

EXAMPLE 1

In one tested example, the alloy matrix material was 17-4PH stainless steel alloy, available from North American Höganäs. The stainless steel alloy included 17.00 weight percent chromium, 3.58 weight percent nickel, 4.07 weight percent copper, 0.39 weight percent niobium, 0.73 weight percent silicon, 0.01 weight percent phosphorus, 0.15 weight percent manganese, 0.01 weight percent carbon, 0.01 weight percent sulfur, and balance iron. The stainless steel alloy was provided in powdered form substantially in ASTM mesh size −325.

The stainless steel alloy particles were combined with aluminum oxide (Al₂O₃) powder in a ball mill drum. In separate tests, the aluminum oxide powder was introduced in amounts of about 5 weight percent, about 10 weight percent, and about 20 weight percent relative to the metal alloy. In this example, the aluminum oxide powder had an average particle size of about 0.3 microns (μm). Spherical ceramic aluminum oxide grinding media was placed within the ball mill drum, and ball milling was conducted for 50 hours at a speed of between about 80 revolutions and about 100 revolutions per minute to achieve in situ coating of the metal particles with the finer aluminum oxide particles.

In this example, the combined powders were hot isostatically pressed at about 2125° F. (about 1160° C.) for 240 minutes in an argon gas environment pressurized to about 14.7 ksi (kilopounds per square inch) (about 101 MPa) to form billets of consolidated particle-matrix composite material. The consolidated billets were then solution treated at 1900° F. (about 1040° C.) for about four hours in an atmospheric pressure, inert gas environment, water quenched, and then aged at 900° F. (480° C.) for four hours to effect precipitation hardening of the metal alloy matrix material.

FIG. 4 is a graph showing test results of the resistivity of the particle-matrix composite material of the embodiments of Example 1 as a function of weight percent of aluminum oxide. As a baseline, the 17-4PH stainless steel alloy with no added aluminum oxide has a resistivity of 786 nano-ohms per meter. With 5 weight percent aluminum oxide, resistivity of the particle-composite matrix material is 1082 nano-ohms per meter, and with 10 weight percent aluminum oxide and 20 weight percent aluminum oxide, the resistivity rises to 1132 nano-ohms per meter and 1471 nano-ohms per meter, respectively.

FIG. 5 is a graph showing test results of the Young's modulus of the particle-matrix composite material of the embodiments of Example 1 as a function of weight percent of aluminum oxide. As a baseline, the 17-4PH stainless steel alloy with no added aluminum oxide has a Young's modulus of 200 GPa. With 5 weight percent aluminum oxide, the particle-matrix composite material has a Young's modulus of 190 GPa. With 10 weight percent aluminum oxide and 20 weight percent aluminum oxide, the Young's modulus rises to 223 GPa and 264 GPa, respectively.

EXAMPLE 2

In another example embodiment, the matrix material was a steel alloy with a composition of 32.44 weight percent manganese, 6.78 weight percent aluminum, 5.74 weight percent chromium, 0.99 weight percent carbon, and balance iron, as well as trace amounts of impurities such as sulfur, phosphorus, and oxygen. This metal alloy was also sourced from North American Höganäs in powdered form. The powdered steel alloy was combined with amounts of aluminum oxide powder to achieve 5 weight percent aluminum oxide and 10 weight percent aluminum oxide relative to the metal alloy in two different tests. In this example, the aluminum oxide powder had an average particle size of about 0.03 micron (μm). The combined powders were ball milled with ceramic grinding balls for about 100 hours at a speed of about 80-100 RPM to coat the metal alloy particles with ceramic powder.

The mixed powders were hot isostatically pressed at 1925° F. (1050° C.) for 240 minutes in an argon gas environment at 14.7 ksi to form particle-matrix composite material billets. The billets were solution treated at 1925° F. (1050° C.) for 45 minutes in an atmospheric pressure, inert gas environment and water quenched. Some billets were aged at 925° F. (500° C.) for 15 minutes to increase strength by precipitation of complex intermetallic structures.

Referring again to FIG. 4, resistivity test results of embodiments of particle-matrix composite materials of Example 2 are shown. With 5 weight percent aluminum oxide, the particle-matrix composite material of Example 2 exhibited a resistivity of 1720 nano-ohms per meter. With 10 weight percent aluminum oxide, the particle-matrix composite material exhibited a resistivity of 2130 nano-ohms per meter. As can be appreciated from FIG. 4, the resistivity of the particle-matrix composite material with a matrix of high-manganese steel (e.g., embodiments of Example 2) may be relatively more sensitive to changes in aluminum oxide content than the particle-matrix composite material with a matrix of 17-4PH stainless steel alloy (e.g., embodiments of Example 1).

Additional non-limiting example embodiments of the disclosure are set forth below.

Embodiment 1

A downhole tool, comprising: a tool body including at least one component comprising a particle-matrix composite material, the particle-matrix composite material comprising: a metal alloy phase, the metal alloy of the metal alloy phase having a resistivity of at least about seven hundred and fifty (750) nano-ohms per meter; and a composite phase comprising ceramic particles dispersed throughout portions of the metal alloy phase, wherein the composite phase extends throughout the particle-matrix composite material in a substantially three-dimensional network, and wherein regions of the composite phase at least partially surround regions of the metal alloy phase that are free of the ceramic particles.

Embodiment 2

The downhole tool of Embodiment 1, wherein the metal alloy comprises at least iron, carbon, and manganese.

Embodiment 3

The downhole tool of Embodiment 2, wherein the mass ratio of manganese to carbon in the metal alloy is about 10:1 or more.

Embodiment 4

The downhole tool of Embodiment 3, wherein the metal alloy comprises at least about twenty weight percent (20 wt %) manganese.

Embodiment 5

The downhole tool of Embodiment 3 or Embodiment 4, wherein the metal alloy comprises at least about thirty weight percent (30 wt %) manganese.

Embodiment 6

The downhole tool of any one of Embodiments 2 through 5, wherein the metal alloy comprises an iron alloy including between about twenty weight percent (20 wt %) and about thirty-five weight percent (35 wt %) manganese, between about five weight percent (5 wt %) and about twelve weight percent (12 wt %) aluminum, and between about 0.3 weight percent (0.3 wt %) and about 1.2 weight percent (1.2 wt %) carbon.

Embodiment 7

The downhole tool of any one of Embodiments 1 through 6, wherein the metal alloy comprises iron and at least about ten weight percent (10 wt %) chromium.

Embodiment 8

The downhole tool of any one of Embodiments 1 through 7, wherein the ceramic particles comprise material chosen from the group consisting of aluminum oxide (Al₂O₃), cubic boron nitride (c-BN) and silicon nitride (Si₃N₄).

Embodiment 9

The downhole tool of any one of Embodiments 1 through 8, wherein the ceramic particles comprise at least about 5 weight percent (5 wt %) of the particle-matrix composite material.

Embodiment 10

The downhole tool of Embodiment 9, wherein the ceramic particles comprise at least about 20 weight percent (20 wt %) of the particle-matrix composite material.

Embodiment 11

The downhole tool of any one of Embodiments 1 through 10, wherein the bulk particle-matrix composite material has an electrical resistivity of at least about 1500 nano-ohms per meter (nΩ/m) and a Young's modulus of at least about 175 GPa.

Embodiment 12

The downhole tool of any one of Embodiments 1 through 11, wherein the downhole tool comprises a tool configured to measure formation resistivity.

Embodiment 13

A method of forming a particle-matrix composite material body, the method comprising: coating particles of metal alloy with relatively finer particles of ceramic; partially compacting the coated particles of metal alloy; and heating the partially compacted coated particles of metal alloy to form a substantially continuous metal alloy matrix with ceramic particles dispersed therein.

Embodiment 14

The method of Embodiment 13, wherein coating particles of metal alloy with relatively finer particles of ceramic comprises intermixing particles of metal alloy with relatively finer particles of ceramic in a ball mill.

Embodiment 15

The method of Embodiment 14, wherein intermixing particles of metal alloy with relatively finer particles of ceramic in a ball mill comprises rotating the ball mill at a speed of about 100 revolutions per minute or less for about 50 hours or more.

Embodiment 16

The method of any one of Embodiments 13 through 15, wherein coating particles of metal alloy with relatively finer particles of ceramic comprises coating particles of metal alloy with an average particle size of between about 40 μm and about 45 μm with particles of ceramic with an average particle size of about 0.3 μm or less.

Embodiment 17

The method of Embodiment 16, wherein coating particles of metal alloy with an average particle size of between about 40 μm and about 45 μm with particles of ceramic with an average particle size of about 0.3 μm comprises coating particles of metal alloy with an average particle size of about 0.03 μm.

Embodiment 18

The method of any one of Embodiments 13 through 17, wherein heating the partially compacted coated particles of metal alloy comprises heating the partially compacted coated particles of metal alloy in a hot isostatic pressing operation.

Embodiment 19

A particle-matrix composite material, comprising: a metal alloy phase, the metal alloy having a resistivity of at least about seven hundred and fifty (750) nano-ohms per meter; and a composite phase comprising ceramic particles dispersed throughout portions of the metal alloy phase, wherein the composite phase extends throughout the particle-matrix composite material in a substantially three-dimensional network, and wherein regions of the composite phase at least partially surround regions of the metal alloy phase that are free of the ceramic particles.

Embodiment 20

The particle-matrix composite of Embodiment 19, wherein the average grain size of the ceramic particles is about one percent (1%) or less of an average grain size of the regions of the metal alloy phase that are free of the ceramic particles.

Although the foregoing description and accompanying drawings contain many specifics, these are not to be construed as limiting the scope of the present disclosure, but merely as describing certain embodiments. Similarly, other embodiments may be devised, which do not depart from the spirit or scope of the present disclosure. For example, features described herein with reference to one embodiment also may be provided in others of the embodiments described herein. The scope of the invention is, therefore, indicated and limited only by the appended claims and their legal equivalents. All additions, deletions, and modifications to the disclosed embodiments, which fall within the meaning and scope of the claims, are encompassed by the present disclosure. 

1. A downhole tool, comprising: a tool body including at least one component comprising a particle-matrix composite material, the particle-matrix composite material comprising: a metal alloy phase, the metal alloy of the metal alloy phase having a resistivity of at least about seven hundred and fifty (750) nano-ohms per meter; and a composite phase comprising ceramic particles dispersed throughout portions of the metal alloy phase, wherein the composite phase extends throughout the particle-matrix composite material in a substantially three-dimensional network, and wherein regions of the composite phase at least partially surround regions of the metal alloy phase that are free of the ceramic particles.
 2. The downhole tool of claim 1, wherein the metal alloy comprises at least iron, carbon, and manganese.
 3. The downhole tool of claim 2, wherein the mass ratio of manganese to carbon in the metal alloy is about 10:1 or more.
 4. The downhole tool of claim 3, wherein the metal alloy comprises at least about twenty weight percent (20 wt %) manganese.
 5. The downhole tool of claim 3, wherein the metal alloy comprises at least about thirty weight percent (30 wt %) manganese.
 6. The downhole tool of claim 2, wherein the metal alloy comprises an iron alloy including between about twenty weight percent (20 wt %) and about thirty-five weight percent (35 wt %) manganese, between about five weight percent (5 wt %) and about twelve weight percent (12 wt %) aluminum, and between about 0.3 weight percent (0.3 wt %) and about 1.2 weight percent (1.2 wt %) carbon.
 7. The downhole tool of claim 1, wherein the metal alloy comprises iron and at least about ten weight percent (10 wt %) chromium.
 8. The downhole tool of claim 1, wherein the ceramic particles comprise material chosen from the group consisting of aluminum oxide (Al₂O₃), cubic boron nitride (c-BN) and silicon nitride (Si₃N₄).
 9. The downhole tool of claim 1, wherein the ceramic particles comprise at least about 5 weight percent (5 wt %) of the particle-matrix composite material.
 10. The downhole of claim 9, wherein the ceramic particles comprise at least about 20 weight percent (20 wt %) of the particle-matrix composite material.
 11. The downhole tool of claim 1, wherein the bulk particle-matrix composite material has an electrical resistivity of at least about 1500 nano-ohms per meter (nΩ/m) and a Young's modulus of at least about 175 GPa.
 12. The downhole tool of claim 1, wherein the downhole tool comprises a tool configured to measure formation resistivity.
 13. A method of forming a particle-matrix composite material body, the method comprising: coating particles of metal alloy with relatively finer particles of ceramic; partially compacting the coated particles of metal alloy; and heating the partially compacted coated particles of metal alloy to form a substantially continuous metal alloy matrix with ceramic particles dispersed therein.
 14. The method of claim 13, wherein coating particles of metal alloy with relatively finer particles of ceramic comprises intermixing particles of metal alloy with relatively finer particles of ceramic in a ball mill.
 15. The method of claim 14, wherein intermixing particles of metal alloy with relatively finer particles of ceramic in a ball mill comprises rotating the ball mill at a speed of about 100 revolutions per minute or less for about 50 hours or more.
 16. The method of claim 13, wherein coating particles of metal alloy with relatively finer particles of ceramic comprises coating particles of metal alloy with an average particle size of between about 40 μm and about 45 μm with particles of ceramic with an average particle size of about 0.3 μm or less.
 17. The method of claim 16, wherein coating particles of metal alloy with an average particle size of between about 40 μm and about 45 μm with particles of ceramic with an average particle size of about 0.3 μm comprises coating particles of metal alloy with an average particle size of about 0.03 μm or less.
 18. The method of claim 13, wherein heating the partially compacted coated particles of metal alloy comprises heating the partially compacted coated particles of metal alloy in a hot isostatic pressing operation.
 19. A particle-matrix composite material, comprising: a metal alloy phase, the metal alloy having a resistivity of at least about seven hundred and fifty (750) nano-ohms per meter; and a composite phase comprising ceramic particles dispersed throughout portions of the metal alloy phase, wherein the composite phase extends throughout the particle-matrix composite material in a substantially three-dimensional network, and wherein regions of the composite phase at least partially surround regions of the metal alloy phase that are free of the ceramic particles.
 20. The particle-matrix composite of claim 19, wherein the average grain size of the ceramic particles is about one percent (1%) or less of an average grain size of the regions of the metal alloy phase that are free of the ceramic particles. 